Add.
Solution: There are many ways to solve this problem. Let's see two ways we can solve it. Place value table Let's line up the numbers by their decimal places. Tens Ones $.$ Tenths $3$ ${9}$ $.$ ${1}$ $5$ $.$ ${0}$ Because $5$ is a whole number, we can add a decimal point and a $0$ behind to make the columns align. Now, let's add each place value column. Tens Ones $.$ Tenths $\overset{1}{{3}}$ ${9}$ $.$ ${1}$ $+$ ${5}$ $.$ ${0}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $4$ $4$ $.$ $1$ Decomposing the numbers We can group the whole numbers together and the decimals together. $\begin{aligned} &({39} + 5) + {0.1}\\\\ &=44 + {0.1}\\\\ &=44.1 \end{aligned}$ $44.1 = 39.1 + 5$